Blue Engine Coolant, Finally in

TL;DR rinse and repeat 

📝 There are only 3.1 liters of coolant, not 5.

What ? Why ?  Read this first 

So, that was supposed to be a nice winter project. The first try at the end of January in a dark evening with freezing temperatures was not really successful as I wasn't able to get the 5 liters of coolant out of the system. Only 3 liters came out. I decided that putting the original fluid back and and topping-up with pink coolant until better days was the best option.

As this week-end of early March 2025 was already granting us with 20°C, it seemed like a good opportunity to try again. 

This time I did preheat the engine with a short drive to the next village and back, I came in with the infrared thermometer showing 87.5°C on each side of the radiator. The OBDII bluetooth dongle was used to monitor the temperature reported by the ECU, it's overestimating the reading by 7°C, as already suspected.

Not many tools are required for the operation, a large flat screwdriver to remove the nosecone and the adjustable spanner were more than enough. The large (gasoline) funnel was used too.

As shown on the first picture, quite a lot of  5 liters containers were required : an empty one to drain the original fluid, 4 with distilled water, and 2 with the blue "long life" coolant bought from the Suzuki dealer.

Leaving the cabin heater fully open all along, the rear of the car was raised using the ramps, the front with the hydraulic jack. I stopped the engine and gently let the pressure out from the expansion bottle (do it very slowly!), then removed the drain plug at the bottom-right of the radiator to fill the empty container. Once the coolant is flowing, the top cap (left side) can be removed as well.

We were once again not able to get more than 3 liters out, and lowering the front of the car didn't change anything. As I had 10 liters of Suzuki blue on hand, I decided that I would drain and throw half of it away in case of doubt that distilled water used for flushing was still present in the circuit.

I closed the drain plug, filled the expansion bottle with distilled water for the first flush, turned the engine on (it was still reporting 60°C), added more water, and closed the top radiator plug once it started pouring. The circuit was filled to the 'MAX' mark of the expansion tank, and we let the engine go back to over 90°C. As the thermostat opens at 85°C and the ECU reading is 7°C off, I needed it to read at least 92°C. Once the electric fan kicked in, the engine was stopped, and the circuit was drained again. The water was quite pink still. And once again, only 3 liters came out.

Rinse and repeat, literally. We flushed the 3 times that were planned since the begining, except it required only 10 liters distilled water instead of the expected 15. The 4th container was intended for the steam generator iron but got an evening out too.

With the 3rd flush coming out rather clear, it seemed that we were ready for the long awaited blue. As an excess of caution, I blew air in the system to see if I could get any liquid out : the expansion tank was closed, I put my mouth on the wider side of the flexible extension of the funnel, small side pressed firmly against the top opening of the radiator. I got very little water out, there was no noise of any remaning liquid after that.

So we closed the bottom plug for the last time and went with the blue. This time I covered the top opening of the radiator with a folded piece of paper towel that I kept in position with a finger until I was sure the circuit was fully purged from air. The top plug was screwed back in place, the engine heated up to temperature. I got the nosecone back on and went for a short drive in the neighbourhood without the hood. The coolant level was topped-up a final time, to the 'max' line.

Using brake cleaner on a piece paper towel, I removed the "-40°C 11/2022" writing from the expansion tank, and wrote "Suzuki blue 03/2025" with a black marker instead.

After a 3 hours drive on the next day, the level was still perfect, with no trace of coolant being purged from the expansion tank cap anymore -as observed since I got the car back from the engine upgrades, and never before-.

Still puzzled by the fact that only 3.1 liters of blue coolant were used, I bought a coolant tester from Amazon. But I was too impatient to wait 2 days to receive it and went on checking that the fluid density was in line with expectations; that is that the weight of 10ml coolant from the car was the same as 10ml coolant from the container, and not "polluted" by distilled water.

Using a 10ml syringe and a precise 50g "diamond" digital scale, I was able to confirm that all is indeed fine with the same weight in the car and in the container, with a density 9% higher than pure distilled water.